Mass

The mass of an object is a measure of the amount of matter it has.^[1] A mountain has a greater mass than a rock, while mass is different weight, which is the vector (directional) product of mass and gravitational acceleration, e.g. 9.81 ms^-2. Weight is sometimes called the force of gravity.

The mass of an object is measurable when a force is exerted on the object. If the mass is greater, the object will have less acceleration (changes in velocity), which is sometimes called inertial mass as it measures the inertia.^[2]

A gigantic mass, like our planet Earth, attracts such a smaller mass as human being to keep the human being from floating away from the Earth's surface. "Mass attraction" is another word for gravity, a force existing between all matters. When measuring the force of gravity exerted on an object, its gravitational mass can be found. Tests of inertial and gravitational mass show that they are the same or almost the same.^[2]

1. ↑ Tsokos, K. A. (2005). Physics for the IB Diploma. Cambridge, United Kingdom: Cambridge University Press. p. 63. ISBN 9780521604055.
2. ↑ ^{2.0 2.1} Knight, Randall Dewey (2003). Physics for scientists and engineers with modern physics : a strategic approach. San Francisco: Pearson/Addison-Wesley. p. 349. ISBN 0-321-24329-3. OCLC 54427199.